A composite material is used for automotive back beams, bonnets, roofs and the like. The composite material is formed by combination of two or more materials, and has a structure in which one material referred to as a reinforcing phase and having a form of fibers, plates or particles is buried in another material referred to as a matrix phase. A reinforcing material must exhibit high strength and high stiffness and include fibers having a certain length or more. Continuous fibers exhibit excellent mechanical strength, stiffness and impact properties as compared with long fiber-reinforced plastics having a length of 5 mm to 50 mm, such as long fiber-reinforced thermoplastics (LFTs) or glass mat-reinforced thermoplastics (GMTs).
Currently, composite materials having a stack structure of continuous fibers and a thermoplastic film are manufactured in order to maximize mechanical properties of the composite materials. However, there is a problem in that the composite materials do not have satisfactory impregnation properties due to weakened interfacial affinity between the continuous fibers and the thermoplastic film and thus do not reach desired properties.